Open Campground with release 1.11 is now available with the operational displays in French, Dutch, Italian and Swedish as well as English. The User's Manual. describes how to set the default language and how to change the language used by the system.
As an example here is what the Reservation List Reservation List in French looks like in French (click on the image to see a large version).

If you would like the system to be made available in another language and are willing to provide translations contact me at norm@opencampground.com.